Carlos Castillo Armas (November 4, 1914-July 26, 1957) was president of Guatemala from July 8, 1954 until his assassination in 1957.

A graduate of the national military academy, he participated in the coup that toppled president Jorge Ubico and General Federico Ponce in 1944. A supporter of assassinated Colonel Jacobo Araña , he was opposed to the perceived liberal direction that the country was taking under Juan José Arévalo and attempted to overthrow his government shortly before the election of his successor, Jacobo Arbenz Guzmán. Castillo Armas was wounded and arrested, but in 1951 he succeeded in escaping to Honduras, where he organized forces opposed to the leftist policies of Arbenz Guzmán.

The United States was also opposed to the nationalization efforts and Arbenz's perceived communism. This led to CIA support for Castillo Armas and his army. In 1954, they invaded Guatemala, forcing Arbenz Guzmán to resign in favor of Carlos Enrique Díaz. Two days later, the army, under Colonel Elfego Monzón deposed Díaz and established a military junta. On July 2, 1954, Castillo Armas was invited to join the ruling junta. Six days later, on July 8, he succeeded Monzón.

On September 1, the remaining members of the military junta resigned, and Carlos Castillo Armas was formally declared president. During his term in office, he purged the government and trade unions of people suspected of left-wing sympathies and reverted the agrarian reforms championed by Arbenz Guzmán, forcing peasants to vacate their newly acquired lands. In 1956 he implemented a new constitution and had himself declared president for four years. He was shot dead in the presidential palace by supporters of Arbenz Guzmán on July 26, 1957. He was succeeded by Luis González López.